Lead-frame configuration for chips

ABSTRACT

The invention relates to a lead-frame configuration with a frame base and multiplicity of lead-frames connected with the frame base, of which each lead-frame is intended to hold a chip, where each lead-frame has two connection plates of which each is intended to connect with a connection of a chip, where the two connection plates of each lead-frame delimit a bridging zone which can be bridged using a chip.

The invention relates to a lead-frame configuration with a frame baseand multiplicity of lead-frames connected with the frame base, of whicheach lead-frame is intended to hold a chip, where each lead-frame hastwo connection plates of which each is intended to connect with aconnection of a chip, where the two connection plates of each lead-framedelimit a bridging zone which can be bridged using a chip.

BACKGROUND

Such a lead-frame configuration is known from patent document U.S. Pat.No. 5,005,282 A. With the known lead-frame configuration, for eachlead-frame in the bridging zone provided between two connection plates,there is a holder section of the lead-frame concerned mainly intended tohold a chip and the chip connected with the lead-frame is also embeddedin a casting compound with which also the two connection plates and theholder section between the two connection plates are mechanicallyconnected together. Because of this structure there is a relativelylarge height in a direction vertical to the plane of the lead-frame.Also in the known design the problem arises that the holder sectionlying between the two connecting plates requires a certain minimumspace, which is disadvantageous in more and more applications and inparticular for connecting chips that are as small as possible with alead-frame in flip-chip technology or connecting the chip connections ofthis chip with the connection plates of a lead-frame in flip-chiptechnology.

SUMMARY OF THE INVENTION

It is an object of the invention to eliminate the difficulties describedabove and to realize an improved lead-frame configuration.

To achieve the above mentioned object, in a lead-frame configurationaccording to the invention in which no chips are yet provided, featuresaccording to the invention are provided so that such a lead-frameconfiguration according to the invention can be characterized in thefollowing manner:

Lead-frame configuration designed strip-like with a frame base and amultiplicity of lead-frames connected with the frame base and lying nextto each other in the strip's longitudinal direction, of which eachlead-frame is intended to hold a chip, where each lead-frame has twoconnection plates and between each connection plate and the frame baseis provided at least one connecting web, and where each connecting plateis intended to connect with a connection of a chip and where the twoconnecting plates of each lead-frame delimit a bridging zone which canbe bridged using a chip, and where the two connecting plates of eachlead-frame abut each other directly without an intermediate section oflead-frame and delimit an air gap as a bridging zone.

To achieve the above mentioned object, in a lead frame configurationaccording to the invention in which each lead-frame has a chip and eachlead-frame is still connected electrically conductively with the framebase, features according to the invention are provided so that such alead-frame configuration according to the invention can be characterizedin the following manner:

Lead-frame configuration designed strip-like with a frame base and amultiplicity of lead-frames connected with the frame base and lying nextto each other in the strip's longitudinal direction, of which eachlead-frame is fitted with a chip, where each lead-frame has twoconnection plates and between each connection plate and the frame baseis provided at least one connecting web, and where each connecting plateis connected with a connection of a chip and where the two connectingplates of each lead-frame delimit a bridging zone bridged by means of achip, and where the two connecting plates of each lead-frame abut eachother directly without an intermediate frame section and delimit an airgap as a bridging zone.

To achieve the above mentioned object, in a lead frame configurationaccording to the invention in which each lead-frame is fitted with achip and each lead-frame is no longer electrically conductivelyconnected with the frame base, features according to the invention areprovided so that such a lead-frame configuration according to theinvention can be characterized in the following manner:

Lead-frame configuration designed strip-like with a frame base and witha multiplicity of lead-frames connected with the frame base and lyingnext to each other in the strip's longitudinal direction, of which eachlead-frame is fitted with a chip, where each lead-frame has twoconnection plates and between each connection plate and the frame basewas originally provided at least one connecting web and where theoriginally provided connecting webs have been disabled, and where eachconnecting plate is connected with a connection of a chip and where thetwo connecting plates of each lead-frame delimit a bridging zone bridgedby means of a chip and where the two connecting plates of eachlead-frame about each other directly without an intermediate framesection and delimit an air gap as a bridging zone, and where for thelead-frames lying next to each other in the strip's longitudinaldirection a connecting strip is provided running in the strip'slongitudinal direction which is connected both with the frame base andwith each of the frames lying next to each other in the strip'slongitudinal linear direction.

The provision of the features according to the invention allows, in aneasily implementable and constructionally simple manner, the lead-frameaccording to the invention to have a particularly compact andspace-saving design at least in the area in which a chip can be or isconnected with the lead-frame, and that in particular the distancebetween two connecting plates of this lead-frame, which connectingplates can be or are bridged by means of a chip is particularly small,which offers the great advantage that the distance between two chipconnections each of which must be or is connected with such a lead-framecan be very small, which is true in the case of a particularly smallchip which because of constant miniaturization is more and more common.In other words a lead-frame configuration according to the invention isideally suitable in particular to hold very small chips withparticularly small distances between chip connections which must beconnected with the lead-frame of the frame configuration in flip-chiptechnology. A further great advantage of a lead-frame configurationaccording to the invention is that it is not necessary to embed the chipconnected with the lead-frame into the casting compound, which meansthat a solution with a particularly small height can be achieved.

In the lead-frame configuration according to the invention the air gapprovided between two connecting plates as a bridging zone can bedesigned so as to be rectilinear and run parallel to the strip'slongitudinal direction of the lead-frame configuration. It has howeverproved very advantageous if the air gap is provided obliquely to thestrip's longitudinal direction, where it has also proved particularlyadvantageous if the air gap is designed essentially S-shaped. Thisdesign is advantageous both with regard to the mechanical stressdistribution in the bridging zone and with regard to the maximumflexibility in relation to the possible positions of the chipconnections of the chips.

These and other aspects of the invention are apparent from the examplesbelow and will be explained using these examples.

BRIEF DESCRIPTION OF THE INVENTION

The invention will be further described with reference to three examplesof embodiments shown in the drawings to which however the invention isnot restricted.

FIG. 1 shows in a plan view a part of a lead-frame configurationaccording to an example of the invention in which lead-frameconfiguration with the lead-frames shown no chips are yet connected.

FIG. 2 shows in a similar manner to FIG. 1 part of a lead-frameconfiguration according to an example of the invention in whichlead-frame configuration with the lead-frames shown a chip is alreadyconnected, and the lead-frame is shown still electrically conductivelyconnected to the frame base.

FIG. 3 shows in a similar manner to FIGS. 1 and 2 a lead-frameconfiguration according to an example of the invention in whichlead-frame configuration with its lead-frames a chip is alreadyconnected and the lead-frames are electrically insulated from the framebase.

DETAIL DESCRIPTION

FIG. 1 shows a lead-frame configuration 1 in part. The lead-frameconfiguration 1 is designed strip-like and has a longitudinal directionof the strip that is indicated in FIG. 1 with an arrow 2. The lead-frameconfiguration 1 has a frame base 3. Connected with the frame base 3 area multiplicity of lead-frames lying next to each other in thelongitudinal direction of the strips 2. In the present case thelead-frames are arranged in two rows 4 and 5. Of the total lead-framesprovided, FIG. 1 shows only six lead-frames 6, 7, 8, 9, 10 and 11 wherelead-frames 6, 7 and 8 belong to the first row 4 and lead-frames 9, 10and 11 to the second row 5. Each lead-frame 6 to 11 is intended to holda chip. In the lead-frame configuration 1 according to FIG. 1, the chipsare not yet connected with the lead-frame configuration 1 or with leadframes 6 to 11 of this configuration 1.

The structure of all lead-frames 6 to 11 is described in more detailbelow where this description is given only using the first-mentionedlead-frame 6.

Each lead-frame 6 to 11, i.e. also lead-frame 6, has two connectingplates 12 and 13. Connecting plates 12 and 13 are separated from theframe base 3 by a first narrow air gap 14 and a first passage 15 and asecond narrow air gap 16 and a third narrow air gap 17 and a secondpassage 18 and a fourth narrow air gap 19. In the first connecting plate12 are provided a full slot 20 and next to this a hole 21 and two halfslots 22 and 23, where the first half slot 22 opens into the firstnarrow air gap 14 and the second half slot 23 into the second narrow airgap 16. In the second connecting plate 13 is also provided a full slot24 and next to this a hole 25 and two half slots 26 and 27, of which thefirst half slot 26 opens into the fourth narrow air gap 19 and thesecond half slot 27 into the third narrow air gap 17. As a result ofproviding the narrow air gaps 14, 16, 17 and 19 and passages 15 and 18,it is achieved that between the first connecting plate 12 and the framebase 3 lie a total of three connecting webs 28, 29 and 30, by means ofwhich the first connection plate 12 is connected both mechanically andelectrically conductively with the frame base 3. In a similar manner,between the second connecting plate 13 and the frame base 3 are providedthree further connecting webs 31, 32 and 33 by means of which the secondconnecting plate 13 is connected with a frame base 3 both mechanicallyand electrically conductively. Each of the two connecting plates 12 and13 is intended to connect with a chip connection of a chip.

The two connecting plates 12 and 13 of the lead-frame 6 delimit abridging zone 34 which can be bridged using a chip. In the lead-frameconfiguration 1 the design is advantageously such that the twoconnecting plates 12 and 13 of the lead-frame 6 and hence of all otherlead-frames 7, 8, 9, 10 and 11 abut each other directly without anintermediate section of the lead-frame 6 or the other lead-frames 7 to11 and delimit a narrow air gap 34 as a bridging zone 34. In the designhere the air gap 34 is provided so as to extend obliquely to thelongitudinal direction of the strips 2. The air gap 34 is alsoessentially S-shaped as is clear from the FIG. 1.

FIG. 2 shows a lead-frame configuration 40 which is obtained by refiningthe lead-frame configuration 1 according to FIG. 1 and differs from theconfiguration 1 in FIG. 1 in that in the lead-frame configuration 40 inFIG. 2, a chip 41, 42, 43, 44, 45, 46 is connected with each lead-frame6 to 11. The chips 41 to 46 are connected with their lead-frames 6 to 11using “flip-chip technology”, which means that each chip 41 to 46 within this case its two chip connections 47, 48 and 49, 50 and 51, 52 and53, 54 and 55, 56 and 57, 58 is placed in rotated position on the twoconnecting plates 12 and 13 of each lead-frame 6 to 11 and connectedelectrically conductively. The connection between the chip connections47 to 58 and the connection plates 12 to 13 of each lead-frame 6 to 11is achieved in this case using a thermo-compression process. Evidentlythe connection between the chip connections 47 to 58 and connectingplates 12 to 13 of each lead-frame 6 to 11 can also be made with otherprocesses known per se.

FIG. 3 shows a further lead-frame configuration 60 which is achieved byrefining the lead-frame configuration 40 in FIG. 2 and differs from theconfiguration 40 in FIG. 2 in that the lead-frames 6 to 11 and the chips41 to 46 connected with these frames 6 to 11 are electrically insulatedfrom the frame base 3. This is achieved in that the connecting webs 28,29, 30 and 31, 32, 33 originally provided between the connecting plates12 and 13 and the frame base 3 are disabled, in that those areas inwhich the said connecting webs 12 to 33 were provided are now providedwith passages 61, 62, 63, 64 and 65 produced by a punching process.

If the passages 61 to 65 were produced without taking precautions thiswould mean that the two connecting plates 12 and 13 of each lead-frame 6to 11 and the chips 41 to 46 connected with the two connecting plates 12and 13 would have no further mechanical connection with the frame base3, with the result that the two connecting plates 12 and 13 of eachlead-frame 6 to 11 and the chips 41 to 46 connected with these wouldfall out of the frame base 3. To prevent this, in the lead-frameconfiguration 60 two connecting straps 66 and 67 are provided in thelongitudinal direction 2 of the strip. The two connecting straps 66 and67 are connected both with the frame base 3 and with each lead-frame 6to 11 via connecting zones. These connecting zones are showndiagrammatically in FIG. 3 with circles 68, 69, 70, 71, 72, 73, 74, 75,76, 77, 78, 79, 80, 81 indicated by dotted lines. Connecting zones 68 to81 are produced of limited area and thus do not extend over the entiresurface area of the connecting straps 66 and 67. Connecting straps 66and 67 here consist of plastic and connecting zones 68 to 81 areproduced by localized warming or heating of the connecting straps 66 and67 made of plastic. Thus connecting zones 68 to 81 can be disabled asrequired, as is described in more detail below.

As, in the frame configuration 60 according to FIG. 3, no electricallyconductive connection remains between connecting plates 12 and 13 ofeach lead-frame 6 to 11 and frame base 3, a test process can now beperformed. In such a test process a contact electrode of a test deviceis brought into electrical connection with each connecting plate 12 and13, whereupon using the test device a test is performed on the chips 41to 46 connected to the plates 12 and 13.

The lead-frame configuration 60 shown in FIG. 3 can be passed on forfurther processing after completion of the necessary test procedure. Forexample the lead-frame configuration 60 according to FIG. 3 can bepassed by the manufacturer of this lead-frame configuration 60 to amanufacturer of contactless communicating chip cards or a manufacturerof contactless RF labels or RF tags. The lead-frame configuration 60according to FIG. 3 is advantageously passed on in roll form, which isparticularly advantageous with regard to the easiest and most efficienttransport.

In the company in which the lead-frame configuration 60 is processedfurther, the connecting straps 66 and 67 together with the connectingplates 12 and 13 connected with the connecting straps 66 and 67 viaconnecting zones 69, 71, 73, 76, 78 and 80, and together with the chips41 to 46, are separated from the frame base 3, and in this separationconnecting zones 68, 70, 72, 74, 75, 77, 79 and 81 are disabled as theparts of the connecting straps 66 and 67 in these connecting zonesremain on the frame base 3. These parts of the connecting straps 66 and67 can however also be separated from the frame base 3. Consequently inthe company in which the lead-frame configuration 60 is processedfurther, the connecting plates 12 and 13 connected with the firstconnecting strap 66 together with chips 41 to 43, and the connectingplates 12 and 13 connected with the second connecting strap 67 togetherwith chips 44 to 46, are available for further processing. During thisfurther processing a unit consisting of two connecting plates 12 and 13and a chip 41 to 46, said unit often being known as a module, isinserted or placed in the end product to be produced. Subsequently thetwo connecting plates 12 and 13 of each module are connected for examplewith the two connection contacts of a transfer coil of the end productconcerned. After this connection of connecting plates 12 and 13 with thecontacts of the transfer coil for example, the relevant connecting strap66 is pulled off connecting plates 12 and 13, whereby then theconnecting zones 69, 71 and 73 or 76, 78 and 80 are disabled as theareas of connecting straps 66 and 67 lying within these connecting zones69, 71, 73, 76, 78 and 80 remain connected with the connecting plates 12and 13. These areas of the connecting straps 66 and 67 can however alsobe separated from the connecting plates 12 and 13.

It should here be pointed out that the connecting straps 66 and 67 andthe connecting plates 12 and 13 connected with the connecting straps 66and 67 via connecting zones 69, 71, 73, 76, 78 and 80 together withchips 41 to 46 need not necessarily be separated from the frame base 3by the further processing company but this could be done by themanufacturer of the lead-frame configuration 60. For example thisseparation could take place after connecting the connecting straps 66and 67 with frame base 3 and with connecting plates 12 and 13 and afterproducing the passages 61 to 65 with a punching process.

It should be stated that the units consisting each of two connectingplates 12 and 13 and a chip 41 to 46 could also be processed furtherusing conventional “pick & place” technology. Here the units consistingof two connecting plates 12 and 13 and a chip 41 to 46 are removedindividually from the frame base 3 in that either the connecting straps66 and 67 are divided in the narrow air gaps 14, 16, 17 and 19 or theunits consisting of the two connecting plates 12 and 13 and a chip 41 to46 are removed from the connecting straps 66 and 67.

In the lead-frame configurations 1 and 40 and 60 described above, thereis the great advantage that the two connecting plates 12 and 13 of eachlead-frame 6 to 11 abut each other directly and are separated from eachother only by a narrow air gap 34. This offers the great advantage thatthe bridging zone 34 formed by the narrow air gap 34 can also be bridgedusing a particularly small chip 41 to 46 in flip-chip technology inwhich the distances between the chip connections are very small. Thusthe lead-frame configurations 1, 40 and 60 are excellently suited forco-operating with particularly small chips. A further advantage in thelead-frame configurations 40 and 60 according to FIGS. 2 and 3 is thatwith these configurations 40 to 60 it is not necessary to embed eachchip 41 to 46 in a casting compound because the particularly narrowbridging zone 34 enables a sufficiently stable mechanical cohesion ofthe connecting plates 12 and 13 connected with the chip connections ofeach chip 41 to 46 to be obtained without casting compound and usingonly the chips 41 to 46 concerned.

1. A lead-frame configuration, the lead-frame configuration beingstrip-like and having a longitudinal direction, with a multiplicity oflead-frames lying next to each other in the longitudinal direction, ofwhich each lead-frame is intended to hold a respective chip, whereineach lead-frame has two connection plates, and wherein each connectingplate is intended to connect with a chip connection of each saidrespective chip and wherein the two connecting plates of each lead-framedelimit a bridging zone which can be bridged using each said respectivechip, and wherein the two connecting plates of each lead-frame abut eachother directly in delimiting the bridging zone.
 2. A lead-frameconfiguration as claimed in claim 1, wherein the bridging zone runs, atleast in part, obliquely to the longitudinal direction.
 3. A lead-frameconfiguration as claimed in claim 1, wherein the bridging zone issubstantially S-shaped.
 4. A chip/lead-frame assembly, the assemblyincluding a chip and a lead-frame configuration, the lead-frameconfiguration being strip-like and having a longitudinal direction, witha multiplicity of lead-frames lying next to each other in thelongitudinal direction, of which each lead-frame has a respective chip,each respective chip having two chip connections, wherein eachlead-frame has two connection plates, and wherein each connecting plateis connected with a chip connection of each said respective chip andwherein the two connecting plates of each lead-frame delimit a bridgingzone bridged by means of each said respective chip, and wherein the twoconnecting plates of each lead-frame abut each other directly indelimiting the bridging zone.
 5. A chip/lead-frame assembly as claimedin claim 4, wherein the bridging zone runs, at least in part, obliquelyto the longitudinal direction.
 6. A chip/lead-frame assembly as claimedin claim 4, wherein the bridging zone is substantially S-shaped.
 7. Alead-frame configuration designed strip-like with a frame base and witha multiplicity of lead-frames connected with the frame base and lyingnext to each other in the strip's longitudinal direction, of which eachlead-frame is fitted with a chip, where each lead-frame has twoconnection plates and between each connection plate and the frame basewas originally provided at least one connecting web and where theoriginally provided connecting webs have been disabled, and where eachconnecting plate is connected with a chip connection of a chip and wherethe two connecting plates of each lead-frame dellmit a bridging zonebridged by means of a chip and where the two connecting plates of eachlead-frame but each other directly without an intermediate section ofthe lead-frame and delimit an air gap as a bridging zone, and where forthe lead-frames lying next to each other in the strip's longitudinaldirection a connecting strap is provided running in the strip'slongitudinal direction which is connected both with the frame base andwith each of the frames lying next to each other in the strip'slongitudinal direction.
 8. A lead-frame configuration as claimed inclaim 7, where the connecting strap is connected both with the framebase and with each of the lead-frames lying next to other in the stripslongitudinal direction via a multiplicity of connecting zones which canbe disabled.
 9. A lead-frame configuration as claimed in claim 7, wherethe air gap runs obliquely with respect to the strip's longitudinaldirection.
 10. A lead-frame configuration as claimed in claim 7, wherethe air gap runs essentially S-shaped.
 11. A lead-frame configuration,the lead frame configuration being strip-like in a longitudinaldirection and having a plurality of lead-frames, each lead frame beingdisposed adjacent to at least one other lead frame in the longitudinaldirection and being provided to support a chip having chip connections,the lead-frame configuration comprising: a lead-frame having two,connection plates, each said connecting plate providing for electricallyconductive connection with a respective one of the chip connections andsaid connecting plates abutting directly in delimiting a bridging zonetherebetween.
 12. A lead-frame configuration as claimed in claim 11,wherein the bridging zone runs, at least in part, obliquely to thelongitudinal direction.
 13. A lead-frame configuration as claimed inclaim 11, wherein the bridging zone is substantially S-shaped.
 14. Alead-frame configuration as claimed in claim 11, wherein the bridgingzone consists of an air gap.
 15. A lead-frame configuration as claimedin claim 11, wherein the bridging zone is provided so as to be bridgedby the chip in connecting the connecting plates with respective chipconnections.
 16. A lead-frame configuration as claimed in claim 11,wherein the two connecting plates abut each other by omitting to disposeany intermediate section of the lead frame between said two connectingplates.
 17. A lead-frame configuration as claimed in claim 11, furthercomprising a frame base.
 18. A lead-frame configuration as claimed inclaim
 17. further comprising at least one connecting web, each saidconnecting web being disposed between a respective connection plate andthe frame base.
 19. A lead-frame configuration as claimed in claim 17,wherein each respective connection plate is mechanically connected tothe frame base, while maintaining electrical insulation therebetween.20. A lead-frame configuration as claimed in claim 19, further providingat least one connecting strap, said connecting strap disposed in thelongitudinal direction and being connected with the frame base and thelead frame of each respective connection plate.